Now I'm no professional by any means, in fact I'm a total wiring novice, but I wanted to post this in case anyone else is going through the same thing and couldn't find any useful information.
Pretty much the xenon headlights have a 4 pin plug. 1 Low beam wire, 1 high beam wire, and 2 grounds/earths.
The non xenon's have a 3 pin plug. 1 Low beam wire, 1 high beam wire, and 1 ground/earth.
Now to wire them together, you'll need the plug from the xenon headlight with some leftover wiring, a soldering iron, heat shrink and some patience.
Step 1: Cut the 3 pin plug off your non xenon car's headlight.
Step 2: Strip the cars headlight wiring and the xenon plug wiring
Step 3: (order is from car to xenon) Connect wires *note you may have to get extra wire just to make the job easier*; Low to low, high to high, and ground to 2 grounds. If you want you can ground the 2nd ground on the xenon plug to the chassis however I just joined mine as I wanted to make it easy to remove all the wiring at once if need be.
Step 4: Test before soldering that you've wired it correctly.
Step 5: Once wired correctly, solder and heatshrink your wiring.
Step 6: Profit.
Attatched is a wiring diagram. No it's not great but my god is it simple and straight to the point.
Hope this helped!
Martin